EP0634834A1 - Linearer spannungsgesteuerter Oszillator - Google Patents

Linearer spannungsgesteuerter Oszillator Download PDF

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Publication number
EP0634834A1
EP0634834A1 EP94304975A EP94304975A EP0634834A1 EP 0634834 A1 EP0634834 A1 EP 0634834A1 EP 94304975 A EP94304975 A EP 94304975A EP 94304975 A EP94304975 A EP 94304975A EP 0634834 A1 EP0634834 A1 EP 0634834A1
Authority
EP
European Patent Office
Prior art keywords
circuit
voltage
transistor
controlled oscillator
current
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP94304975A
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English (en)
French (fr)
Inventor
Irving G. Post
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
AT&T Corp
Original Assignee
AT&T Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by AT&T Corp filed Critical AT&T Corp
Publication of EP0634834A1 publication Critical patent/EP0634834A1/de
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03C—MODULATION
    • H03C3/00—Angle modulation
    • H03C3/10—Angle modulation by means of variable impedance
    • H03C3/12—Angle modulation by means of variable impedance by means of a variable reactive element
    • H03C3/14—Angle modulation by means of variable impedance by means of a variable reactive element simulated by circuit comprising active element with at least three electrodes, e.g. reactance-tube circuit
    • H03C3/145—Angle modulation by means of variable impedance by means of a variable reactive element simulated by circuit comprising active element with at least three electrodes, e.g. reactance-tube circuit by using semiconductor elements
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
    • H03B5/08—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance
    • H03B5/12—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device
    • H03B5/1203—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device the amplifier being a single transistor
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
    • H03B5/08—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance
    • H03B5/12—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device
    • H03B5/1231—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device the amplifier comprising one or more bipolar transistors
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
    • H03B5/08—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance
    • H03B5/12—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device
    • H03B5/1237—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device comprising means for varying the frequency of the generator
    • H03B5/1271—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device comprising means for varying the frequency of the generator the frequency being controlled by a control current, i.e. current controlled oscillators
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
    • H03B5/08—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance
    • H03B5/12—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device
    • H03B5/1237—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device comprising means for varying the frequency of the generator
    • H03B5/1293—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device comprising means for varying the frequency of the generator having means for achieving a desired tuning characteristic, e.g. linearising the frequency characteristic across the tuning voltage range
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B2200/00—Indexing scheme relating to details of oscillators covered by H03B
    • H03B2200/003—Circuit elements of oscillators
    • H03B2200/005—Circuit elements of oscillators including measures to switch a capacitor
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B2200/00—Indexing scheme relating to details of oscillators covered by H03B
    • H03B2200/006—Functional aspects of oscillators
    • H03B2200/0092—Measures to linearise or reduce distortion of oscillator characteristics

Definitions

  • This invention relates to voltage controlled oscillators and, more particularly, to voltage controlled oscillators where the frequency deviation is required to be linear with respect to the control voltage.
  • the modulation and demodulation of fm signals may employ an oscillator whose frequency varies with the modulating or control voltage.
  • Oscillators whose frequency variation is produced in accordance with a control voltage are called voltage controlled oscillators and many of these circuits employ a varactor diode as the voltage responsive variable reactance component.
  • the varactor diode is a popularly used element in such circuits, it is rather expensive and, in certain applications such as small, hand-held cellular telephones where only a low supply voltage is available, there may not be sufficient voltage available to permit the varactor diode to undergo a sufficient range of reactance variation to produce the desired frequency excursion of the oscillator. In addition, it is desirable to have the frequency excursion vary linearly with the control voltage. Accordingly, an alternative to the use of the varactor diode in voltage controlled oscillators circuits is desirable.
  • the emitter of transistor Q1 is in series with transistor Q16 and establishes a (dc) reference voltage at the base of transistors Q3 and Q4.
  • Transistors Q1, Q14, Q15, Q16 and Q19 are high impedance bias current sources and do not enter into the operation of the oscillator at the frequency of oscillation.
  • Leads IIN1 and IIN2 are current source leads from the power supply, Fig. 2.
  • a series-resonant, negative-resistance loop for ac current is seen to be comprised of the the emitter circuit of emitter-follower transistor Q2, the series resonant combination of inductor L0 and capacitor C0, the emitter-collector paths of grounded-base transistors Q3 and/or Q4 and resistor R6. While an inductor-capacitor combination is shown connected to the emitter of transistor Q4, it should be apparent that a crystal, ceramic, or SAW resonator may be employed instead.
  • Transistor Q2 is connected as an emitter-follower stage to provide a low impedance drive for the resonant circuit comprising inductor L0 and capacitor C0.
  • transistor Q4 develops an output voltage across load resistor R6 in its collector circuit to provide the driving voltage for the base of transistor Q2.
  • R6 In order to provide sufficient voltage gain for oscillation, R6 must be larger than the total resistance in series with the resonant circuit.
  • Leads IIN1 and IIN2 are the output leads of the high impedance, current source power supply of Fig. 2.
  • the ac emitter current of transistor Q2 passing through the series resonant circuit of L0 and C0 is shared between the emitter-collector paths of transistors Q3 and Q4, thereby effectively causing more or less ac current to flow through capacitor CX.
  • transistor Q4 When transistor Q4 is off, substantially all of the emitter current of transistor Q2 flows through capacitor CX and the emitter-collector path of transistor Q3 and develops a feedback voltage across R6.
  • transistor Q3 When transistor Q3 is off and transistor Q4 is on, substantially all of the emitter current of transistor Q2 bypasses capacitor CX and flows only through the emitter-collector path of transistor Q4 to develop the the feedback voltage across R6. Accordingly, capacitor CX is or is not effectively inserted in series with capacitor C0 of the resonant circuit thereby affecting the capacitive reactance of the series resonant circuit.
  • transistor Q4 When transistor Q4 is on and tranistor Q3 is off, substantially all of the (ac) emitter current of transistor Q2 flows through lead IIN2.
  • Capacitor CX is thereby effectively removed from the series resonant circuit causing its capacitive reactance to be at the value determined by C0 alone.
  • the ratio of the collector currents between leads IIN1 and IIN2 determines the relative amount of capacitor CX's capacitance that is effectively in series with capacitor C0, thereby determining the amount of capacitive reactance of the series resonant circuit and its frequency of oscillation.
  • I cause the frequency of the resonant circuit to vary more linearly with control voltage than has heretofore been possible by causing the sum of the two emitter currents to be constant as well as by causing the current of Q3 to vary as the square root of control voltage V IN , Fig. 2.
  • current source 11 supplies current directly to the base of transistor Q3 and, through transistor Q2, to the base of transistor Q1.
  • the base of transistor Q3 is two diode drops above ground.
  • the base of transistor Q1 is connected to the output of the OPAMP.
  • Q1 and the OPAMP form an operational amplifier combination. Since Q1 inverts the output of the OPAMP, the input INP of the OPAMP is the negative input and the input INN is the positive input. For a high-gain operational amplifier, the negative input becomes a virtual ground.
  • the OPAMP is employed to cause a current proportional to VIN to flow in Q1 and to sink the current flowing from the emitter of Q2. Note, that the OPAMP can both source and sink current.
  • the V be of transistor Q1 is proportional to the log of transistor Q1's emitter current.
  • V be 3 + V be 4 V be 1 + V be 2 where the subscript number on V be indicates the respective transistors.
  • Equation (3) therefore represent a multiplication of the values represented by the base-emitter currents of transistors Q3 and Q4.

Landscapes

  • Inductance-Capacitance Distribution Constants And Capacitance-Resistance Oscillators (AREA)
  • Stabilization Of Oscillater, Synchronisation, Frequency Synthesizers (AREA)
EP94304975A 1993-07-14 1994-07-06 Linearer spannungsgesteuerter Oszillator Withdrawn EP0634834A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US92141 1993-07-14
US08/092,141 US5469119A (en) 1993-07-14 1993-07-14 Linear voltage-controlled oscillator using fixed capacitors in lieu of varactors

Publications (1)

Publication Number Publication Date
EP0634834A1 true EP0634834A1 (de) 1995-01-18

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP94304975A Withdrawn EP0634834A1 (de) 1993-07-14 1994-07-06 Linearer spannungsgesteuerter Oszillator

Country Status (3)

Country Link
US (1) US5469119A (de)
EP (1) EP0634834A1 (de)
JP (1) JPH0758546A (de)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4132964A (en) * 1977-07-28 1979-01-02 National Semiconductor Corporation Non-linearity correction in wide range voltage controlled oscillators
DE2803400B1 (de) * 1978-01-26 1979-07-19 Siemens Ag, 1000 Berlin Und 8000 Muenchen Schaltung zur Frequenzvariation eines spannungsgesteuerten Oszillators
DE3246295A1 (de) * 1982-12-14 1984-06-14 Siemens AG, 1000 Berlin und 8000 München Frequenzmodulierbarer oszillator
GB2141299A (en) * 1983-05-25 1984-12-12 Sony Corp Variable frequency oscillator
US4492934A (en) * 1981-02-12 1985-01-08 Tokyo Shibaura Denki Kabushiki Kaisha Voltage controlled oscillator with linear characteristic

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3553380A (en) * 1968-10-25 1971-01-05 Itt Multiplexing system
US4230953A (en) * 1978-07-31 1980-10-28 National Semiconductor Corporation Non-linear control circuit
US4684904A (en) * 1986-01-06 1987-08-04 The United States Of America As Represented By The Secretary Of The Air Force Low phase noise two port voltage controlled oscillator
US4709409A (en) * 1986-08-25 1987-11-24 Ma John Y TVRO receiver with surface mounted high frequency voltage-controlled oscillator

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4132964A (en) * 1977-07-28 1979-01-02 National Semiconductor Corporation Non-linearity correction in wide range voltage controlled oscillators
DE2803400B1 (de) * 1978-01-26 1979-07-19 Siemens Ag, 1000 Berlin Und 8000 Muenchen Schaltung zur Frequenzvariation eines spannungsgesteuerten Oszillators
US4492934A (en) * 1981-02-12 1985-01-08 Tokyo Shibaura Denki Kabushiki Kaisha Voltage controlled oscillator with linear characteristic
DE3246295A1 (de) * 1982-12-14 1984-06-14 Siemens AG, 1000 Berlin und 8000 München Frequenzmodulierbarer oszillator
GB2141299A (en) * 1983-05-25 1984-12-12 Sony Corp Variable frequency oscillator

Also Published As

Publication number Publication date
US5469119A (en) 1995-11-21
JPH0758546A (ja) 1995-03-03

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